This invention relates to an improved process for manufacturing perfluoroethanesulfonyl fluoride and/or perfluorodiethylsulfone. More particularly, the present invention relates to using a two-part catalytic system for preparing perfluoroethanesulfonyl fluoride and/or perfluorodiethylsulfone.
Perfluoroethanesulfonyl fluoride (PESF)and perfluorodiethylsulfone (PDES) may be used in a variety of applications. For example perfluoroethanesulfonyl fluoride is an intermediate in the manufacture of lithium bisperfluoroethanesulfonylimide (the BETI salt, available from 3M Company as FC-130), which is used as an electrolyte commercially in rechargeable lithium batteries. PESF may also be used as an intermediate in the manufacture of perfluoroethanesulfonate and various methide anions such as xe2x88x92C(SO2C2F5)3. Perfluorodiethylsulfone may be used as a solvent, heat exchange fluid or as a reactive intermediate in the manufacture of perfluoroethanesulfonate and perfluoroethanesulfonyl amide. Perfluorodiethylsulfone may also be used as an initiator for preparing amorphous copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP). (See, U.S. Pat. No. 5,637,663).
Fluoride catalyzed reactions of fluoroolefins, such as TFE and HFP, with SO2F2 to produce perfluoroethanesulfonyl fluoride (PESF), perfluorodiethylsulfone (PDES), and perfluoro-iso-propanesulfonyl fluoride, respectively, are known in the art. Whereas the reaction of HFP with SO2F2 to produce perfluoro-iso-propanesulfonyl fluoride proceeds readily under moderate reaction conditions (50-100xc2x0 C.) using conventional one-part metal fluoride catalysts (e.g., KF and CsF), the corresponding metal fluoride-catalyzed reaction of TFE with SO2F2 to produce PESF and PDES is relatively sluggish. Generally, the latter reaction requires high temperatures (xe2x89xa7100xc2x0 C.), long reaction times and/or very high catalyst loadings to achieve reasonable conversions or practical rates of reaction.
For example, in J. Org. Chem., 33(1), 344 (1968) and GB Patent No. 1,189,561, S. Temple describes the catalytic reaction of TFE with SO2F2 using CsF as the catalyst and diglyme as the solvent to produce PDES. Under 100xc2x0 C., this reaction is impractically slow. High temperatures (and pressures) and high catalyst loadings are required to achieve practical rates of conversion.
U.S. Pat. No. 3,542,864 ((Koshar) discloses the reaction of TFE with SO2F2 in a solvent such as dimethylformamide or acetonitrile using an alkali metal fluoride such as CsF to produce PESF. But at moderate reaction temperatures (and pressures) this reaction is impractically slow.
U.S. Pat. No. 5,780,682 (Zavilla et al.) discloses the preparation of fluorinated alkyl sulphonyl halides by reacting a fluorinated unsaturated hydrocarbon with a sulfuryl halide. The reaction is carried out in the presence of at least a catalytic amount of fluoride in a solvent comprising an alkyl sulfonyl or alkylsulfoxide compound. No reactions of TFE are exemplified.
Thus, for economic reasons and due to pressure limitations of process equipment used in large scale manufacturing, the need exists for a more active catalyst system that accelerates the rate of reaction of TFE with SO2F2 and allows preparation of PESF and PDES at lower temperatures and pressures and at a reasonable rate while also providing control of the PESF/PDES product distribution.
The present invention provides a process for preparing perfluoroethanesulfonyl fluoride and/or perfluorodiethylsulfone using a two-part catalytic system. Advantageously, the catalytic system of the present invention provides higher catalytic activity and significantly faster rates of reaction under a given set of reaction conditions versus known one-part catalysts.
The present invention comprises a method of preparing perfluoroethanesulfonyl fluoride and/or perfluorodiethylsulfone from tetrafluoroethylene (TFE) and sulfuryl fluoride (SO2F2). The present invention comprises a catalytic process for the preparation of perfluoroethanesulfonyl fluoride and/or perfluorodiethylsulfone comprising the steps of:
(a) reacting in the presence of a two-part catalyst system in a polar aprotic organic solvent:
(i.) tetrafluoroethylene, and
(ii.) sulfuryl fluoride;
wherein said two-part catalyst system comprises a metal fluoride and a crown ether; and
(b) recovering perfluoroethanesulfonyl fluoride or perfluorodiethylsulfone, or a mixture thereof.
Another embodiment of the present invention is a process further comprising combining an immiscible, highly fluorinated co-solvent with the polar aprotic organic solvent.